METHOD FOR COATING A MECHANICALLY HIGHLY LOADED SURFACE OF A COMPONENT, AND COATED COMPONENT ITSELF

Abstract

The invention relates to a method for coating a mechanically highly loaded surface (2) of a component (1) consisting of a hardened steel with a nitrogen and/or carbon component with an adherent or functional coating (4) for surface treatment, wherein a metallic binding material (5) is introduced into the surface (2) prior to the application of the adherent or functional coating (4) to create a graduated diffusion barrier zone (3) conforming to the surface with a proportion of metal nitride and/or metal carbide increasing towards the surface (2).

Claims

1. A process for coating a mechanically highly stressed surface (2) of a component (1) comprising a hardened steel having a proportion of nitrogen and/or carbon with a bonding layer or functional layer (4) for surface upgrading, characterized in that a metallic binder material (5) is introduced into the surface (2) in order to create a gradated diffusion barrier zone (3) which conforms to the surface and has a proportion of metal nitride and/or metal carbide which increases in the direction of the surface (2) before application of the bonding layer or functional layer (4).

2. The process as claimed in claim 1, characterized in that the introduction of the metallic binder material (5) is carried out by implantation or inward diffusion.

3. The process as claimed in claim 2, characterized in that the introduction of the metallic binder material (5) is in the case of inward diffusion carried out at a process temperature of from 200 to 500° C.

4. The process as claimed in claim 1, characterized in that the introduction of the metallic binder material (5) is carried out with a penetration depth (T) of up to 200 nanometers.

5. A component which has been coated by the process as claimed in claim 1, characterized in that the metallic binder material (5) for producing the diffusion barrier zone (3) is selected from a binder metal group comprising chromium, manganese, molybdenum, tungsten.

6. The component as claimed in claim 5, characterized in that the bonding layer or functional layer (4) is configured as a chromium alloy or titanium alloy layer for promoting adhesion or a hard material layer for surface upgrading.

7. The component as claimed in claim 5, characterized in that the bonding layer or functional layer (4) is configured as a hard material layer comprising diamond-like carbon (DLC).

8. The component as claimed in claim 5, characterized in that the component (1) comprises a nitrided or carburized chromium-nickel steel as hardened steel alloy.

9. A high-pressure valve or high-pressure pump of a fuel injection system of a motor vehicle, which is equipped with a component (1) as claimed in claim 5.

10. The high-pressure valve as claimed in claim 9, wherein the component (1) is configured as a nozzle needle or a control valve component of a fuel injector.

11. The process as claimed in claim 4, characterized in that the introduction of the metallic binder material (5) is carried out with a penetration depth (T) of up to 100 nanometers.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Further measures for improving the invention will be described in more detail below together with the description of a preferred working example with the aid of the figures. The figures show:

[0015] FIG. 1 a schematic longitudinal section through a coating on the surface of a component with diffusion barrier zone, and

[0016] FIG. 2 a schematic depiction of the sequence of steps for obtaining a coating as per FIG. 1.

DETAILED DESCRIPTION

[0017] In FIG. 1, a component 1 which is depicted here in a sectional view consists, in a region close to the surface, of a hardened steel having a proportion of nitrogen and carbon. The surface 2 of the component 1 has a fissured surface topology corresponding to the metal microstructure, which shows up here on the microscopic scale. A gradated diffusion barrier zone conforming to the corresponding surface is introduced in such a way that there is a proportion of metal nitride and metal carbide which increases in the direction of the surface 2 and displays a barrier action against further nitrogen and carbon being able to escape to the outside from the hardened steel.

[0018] A bonding or functional layer 4 has been applied by means of a plasma-enhanced CVD process to the surface 2 which has been modified in this way. The bonding or functional layer 4 is in this working example configured as a hard material layer consisting of DLC.

[0019] In FIG. 2, a metallic binder material 5 is first applied for coating the surface 2 of a component 1 which consists of a nitrided or carburized chromium-nickel steel as hardened steel alloy. The metallic binder material 5 here is a chromium powder. As a result of the component 1 being heated together with the applied metallic binder material 5 to a temperature of about 200° C., the metallic binder material 5 penetrates into the component 1 over the surface 2, so that a gradated diffusion barrier zone 3 which has an increasing proportion of chromium-based nitride and chromium-based carbide in the direction of the surface 2 is formed in the component 1. Here, the gradated diffusion barrier zone 3 created in this way conforms to the surface.

[0020] The bonding or functional layer 4, which serves for the final surface upgrading in order to increase the mechanical stressability of the component 1, is subsequently applied to the surface 2 of the component 1.

[0021] The invention is not restricted to the above-described preferred working example. Rather, modifications of this are also conceivable, and these are also encompassed by the scope of protection of the claims below. Thus, it is also possible, for example, firstly to apply an intermediate bonding layer instead of a final functional layer to the component surface, with this intermediate bonding layer subsequently being provided with the functional layer. This layer structure leads, depending on the combination of materials, to a further-improved layer adhesion.